Investigation of structural, thermal, and flow properties of porous and biomimetic tree-like structure produced by additive manufacturing

In this study, the structural and thermal properties of porous plate specimens produced via the SLM method were investigated, along with the transpiration cooling performance of biomimetic tree-like structures fabricated using the same method. These structures were specifically analyzed to evaluate the effectiveness of the transpiration cooling method for components exposed to high temperatures, such as aircraft engines. Thermal conductivity experiments, surface roughness assessments, and microhardness measurements conducted on porous plates produced from CoCrW, 316L, and Ti6Al4V powders via SLM revealed that the physical, mechanical, thermal, and surface properties of the materials are significantly influenced by SLM process parameters. For porous plate specimens produced from all three materials, an increase in material density resulted in higher hardness values. Among the most notable differences observed in specimens fabricated under varying energy densities was the porosity. Higher energy densities led to a decrease in porosity across all three materials. While 316L and CoCrW specimens exhibited similar porosity levels at comparable energy densities, Ti6Al4V specimens required relatively higher energy densities to achieve lower porosity levels. As a result, it was concluded that process parameters play a critical role in designing products for heat and flow applications in additive manufacturing. Among the porous plate specimens produced via SLM, those made with 316L powder demonstrated the best thermal performance in thermal conductivity measurements. Consequently, biomimetic tree-like structures for heat transfer experiments were fabricated using 316L powder via the SLM process. Among these structures, the N7 sample (30×30×30 mm), which featured an initial channel diameter of 500 μm, a branching ratio of 0.65, and a channel duplication distance six times the diameter, exhibited the best thermal performance. Particle Image Velocimetry (PIV) was also employed on this sample to obtain vector maps. The study showed that optimal heat transfer results were achieved by increasing the channel diameter while decreasing the branching ratio and duplication distance.